The present invention relates generally to two-part fasteners, and more particularly to fasteners adapted for relatively quick assembly by pressing the fastener together.
Numerous fasteners of this general type are known and commercially available. Such fasteners are disclosed in Bailet et al., U.S. Pat. No. 4,369,012; Hutchinson, U.S. Pat. No. 5,113,553; Schaeffer, U.S. Pat. No. 2,118,361; U.K. Pat. No. Application 2249804; Anderson, U.S. Pat. No. 5,775,863 and Norway Pat. No. 72788.
In particular, Anderson discloses a fastener with a clip that includes forward split collar sections movable between a normally closed position for interlocking engagement with longitudinally spaced ribs on a post, and an open position for installation and removal of the clip from the post. Centrally located elastic bands join the collar sections, and a pair of wings extend rearwardly from the elastic bands such that squeezing the wings together opens the collar. The split collar and ribs are provided with complimentary angled surfaces such that the normally closed collar sections snap over the ribs if the clip is pushed onto the post without squeezing the wings together.
Arrangements of varying similarity are shown in the above-mentioned patents. Although the terminology is different, Schaeffer and Bailet disclose fasteners that include split collars, wings, and resilient connections therebetween for manual separation of the collar to enable installation onto a threaded post or a post formed with longitudinally spaced detents or protrusions. Unfortunately, split collars that are designed to be manually separated may also be inadvertently separated upon application of certain external forces, and the fastener may loosen after being assembled together.
For example, if external forces are exerted on the collar sections in the direction toward the elastic connection and in such a way as to impart a torque on the collar section, the collar sections will tend to separate from one another and from the post. If such forces are sufficiently large, the collar sections may disengage from the post, and in the presence of reversing load conditions, the clip can "walk" rearwardly on the post. Such loading conditions can occur, for example, from high winds acting on a sign when the wind induces a resonant condition in the sign post.
The occurrence of this condition is precluded in Schaeffer and most of the embodiments of Bailet by providing the split collar with a nose section that is snugly received into a recess formed in the contacting member. In such arrangements, inadvertent separation is avoided because the external forces are directed inwardly through the nose of the collar toward the center of the post, rather than rearwardly toward the elastic bands. However, where it is desired to utilize such quick-assembly fasteners without the need to provide a recess sized for receiving the forward portion of the clip in the contacting member, such as disclosed in Anderson and certain embodiments shown in Bailet, there is a need for an improved fastener adapted to prevent inadvertent loosening of the clip from the post.